The present invention relates to methods and devices for joining pipes and for attaching pipes to connecting pieces on T-pipes, bends and equipment such as valves, faucets, measuring instruments, etc.
It is previously known to slide pipes or tubes onto the outside of connecting pieces and to clamp them securely to the connecting piece by means of a clamping device. It is also known to employ a fitting sleeve that covers both pipes or tubing ends, or the pipe/tubing end and a connecting piece. Further, it is known to use gaskets in connection with such seals.
According to the prior art, pipes are usually joined by means of welding, soldering, compression joints, clamping sleeve couplings or flanges. The various methods have their strong and weak aspects and have therefore won favor in different areas. In the art of sanitary equipment, for pipes of pliable material such as plastic, it is particularly the methods employing clamping rings and clamping sleeves that have gained ground, as well as welding for weldable plastic.
For pipes of annealed copper, the common practice involves soldering to bends, T-pipes and sockets, this being presently the only permissible method for installations that are to be concealed in walls or flooring.
A common coupling method for open installations which is both rapid and simple involves compression joints in combination with support linings. The disadvantage of this method is that the pipes are easily damaged as a result of the assembly method, which results in leakage after a period of use. For this reason it is not permitted to use this method where the pipes are to be built into walls or floors.
Welding methods have been developed for plastic piping, but In practice this is a time-consuming process compared to use of compression joints and, moreover, may only be used on weldable plastic, while other types of plastics are steadily gaining an increasing share of the market.
A number of different types of compression joints are also available for plastic, some of them for use in combination with support linings, while others are intended to be used without them. One of such types without support linings is damaging to the surface of the pipe under the clamping ring, and therefore cannot be used on pipes having a diffusion block at the surface. Couplings for pipes carrying hot water require support linings.
It is a common feature of all types of compression joints that the compression of the clamping ring should take place through axial movement of the adjacent parts, and for this reason the effective width of the clamping ring must be limited. The combination of axial movement for the ring's adjacent parts, achieved by virtue of standard threads and the narrow clamping ring, affords poor control with the surface pressure between the ring and the pipe, which easily results in damage to the pipe.
The numerous parts in a compression joint give it a considerable weight and make it expensive to produce.